The Angle Kappa in Dominant and Non-Dominant Eye

PURPOSE: To evaluate differences between dominant and non-dominant eyes by analyzing angle kappa in dominant and non-dominant eyes. METHODS: Fifty-seven subjects who had best corrected visual acuity 20/20 in the better-seeing eye and no underlying ocular disease were recruited. Ocular dominance was determined using the hole-in-the-card test. Corneal topography, refractive error, intraocular pressure (IOP), and axial length were evaluated in both eyes. RESULTS: On corneal topography examination, the angle kappa and white-to-white measurements were significantly smaller in the dominant eye than the non-dominant eye (p = 0.013 and p = 0.045, respectively). However, no significant differences in sim K's' astigmatism (p = 0.210), central corneal thickness (p = 0.533), and anterior chamber depth (p = 0.216) were observed. In addition, cylindrical powers of the subjects measured by autorefraction (AR) were significantly lower in the dominant eye (p = 0.026); however no differences in spherical equivalent measured by AR (p = 0.061), IOP measured using pneumonic tonometer (p = 0.536), or axial length measured using laser biometry (p = 0.093) were observed. CONCLUSIONS: In this study, we found the angle kappa a new factor in determining the dominant and non-dominant eye. Difference in axial length and spherical equivalent between dominant and non-dominant eye may be associated with the difference in angle kappa.

Retinal Nerve Fiber Layer Thickness and Optic Disc Parameters in Dominant Compared with Non-Dominant Eyes

PURPOSE: To investigate the comparison of retinal nerve fiber layer (RNFL) thickness and optic disc parameters measured by optical coherence tomography (Cirrus HD-OCT(R)) in dominant and non-dominant eyes. METHODS: Seventy-one subjects without underlying ocular disease were recruited for the present study. Ocular dominance was determined using the hole-in-the-card test. Comprehensive standardized eye examinations were performed. Scans of the optic disc and RNFL were performed using OCT. RESULTS: The mean intraocular pressure (IOP) of the dominant eye was higher than its counterpart (p = 0.025). No significant differences were observed in uncorrected visual acuity, refractive error and axial length between dominant and non-dominant eyes (p = 0.235, 0.180, 0.850). No RNFL and optic disc features were identified in the dominant from non-dominant eyes. CONCLUSIONS: Although dominant eyes tended to have higher IOP than non-dominant eyes, no consistent ocular structural differences between dominant and non-dominant eyes with the use of OCT were found.

The Refractive Errors of Dominant and Non-dominant Eyes

PURPOSE: To evaluate differences between dominant and non-dominant eyes through analyzing refractive factors in determination of the dominant eye. METHODS: Sixty-two subjects without underlying ocular disease were recruited. Ocular dominance was determined using the hole-in-the-card test. Uncorrected visual acuity, refractive error, and intraocular pressure (IOP) were checked in both eyes. RESULTS: Mean uncorrected visual acuity of the dominant and non-dominant eye were 0.41 and 0.39, respectively. The number of patients whose uncorrected visual acuity of the dominant eye was superior to the non-dominant eye was 18(29%), and inferior to the non-dominant eye was 18(29%). Mean refractive power in the dominant eye was -3.2 diopter and -3.43 diopter degrees in the non-dominant eye, therefore no difference in degrees of myopia between the groups (P=0.282) was observed. The number of patients whose dominant eye had a greater degree of myopia than the non-dominant eye was 24(39%) and the patients with a lower degree of myopia in the dominant eye was 32(52%). Astigmatism of the dominant eye was lower than the non-dominant eye in 35(56%) of the patients, thus a significant relationship was shown between astigmatism and the dominant eye (P=0.0014). The mean IOP of the dominant eye was 15.4 mmHg and the non-dominant eye was 15.7 mmHg, showing no significant difference between eyes. CONCLUSIONS: The dominant eye showed a lower degree of astigmatism than the non-dominant eye. The previous belief that myopia is more progressed in the dominant eye than the non-dominant eye because of excessive accommodative use of the dominant eye requires further study.

Ocular Dominance Determined by Near Point of Convergence Test in Intermittent Exotropia

This study was designed to validate the usefulness of the near point of convergence(NPC)test in determination of dominant & non-domnant eyes in intermittent exotropia patients. We performed NPC test in 36 intermittent exotrpic patients, and then, determined the non-dominant eye which deviated outward beyond the NPC. The dominant eyes determined by the NPC were compared to those that were determined by amblyopia, sensory fusion and photophobia. Best corrected visual acuity was used to divide patients into two groups : 26 patients without amblyopia, and 10 with amblyopia. Among the amblyopia group, if the eyes with better visual acuity were taken as dominant eyes, then eight(80%)cases were identical with the NPC test and two(20%)cases were different. Ten patients had sensory anomaly, and among then, nine(90%)cases were identical with the NPC test and one(10%)case was different. Twenty six(64%)patients had photophobia in one eye and all(100%)cases were identical with the NPC test. In intermittent exotropia, determination of dominant eye by the NPC test showed high coincidence with other tests. Therefore, we suggest that the NPC test is an easy and accurate method in determining either the dominant or non-dominant eye for surgery.

The Surgical Results of Medial Rectus Muscle Resection of Dominant Eye and Lateral Rectus Muscle Recession of Non-dominant Eye in Intermittent Exotropia

Intermittent Exotropia has been treated by various surgical methods such as bilateral medial rectus resection, lateral rectus recession and medial rectus resection of deviating eye, and bilateral lateral rectus recession. However, the outcomes of such operations are unsatisfactory because of high incidence of postoperative undercorrection and overcorrection. Authors have performed a surgical method which is the medial rectus muscle resection of dominant eye and lateral rectus muscle recession of non-dominant eye in 68 patients. Authors considered the outcome successful if patients achieve deviation between 10 PD of exophoria and 5 PD of esophoria, good stereopsis, no suppression and no manifest deviation. The success rate was 83.8% (57/68) and there was no overcorrection over 6 months follow-up. As postoperative complications, 5 cases of temporary turning of face and 3 cases of asymmetric palpebral fissure were seen. Therefore, these results suggest that medial rectus resection of dominant eye and lateral rectus recession of non-dominant eye in intermittent exotropia may be an alternative surgical method for intermittent exotropia. However, further studies are necessary to determine the exact surgical amounts and mechanism of this surgical method.